Exemplary embodiments of the present invention relate to a battery with a plurality of individual cells connected in series and/or in parallel to one another, and at least one cooling plate arranged on the pole side on the individual cells, with current drain tabs of electric poles of the individual cells being thermally coupled with the cooling plate and being angled such that they extend parallel to the cooling plate.
A battery for use in motor vehicles, in particular in motor vehicles with a hybrid drive, electric drive or fuel cell vehicles, usually has a cell block consisting of a plurality of battery cells, for example lithium ion cells, connected electrically in series and/or in parallel.
The battery cells have to be cooled in order to dissipate the resulting lost heat. A cooling device that is thermally connected to the battery cells is typically used for this purpose.
A battery, in particular a lithium ion battery, with a plurality of individual cells connected in series and/or in parallel to one another, and a cooling plate arranged on the pole side on the individual cells is known from the not yet published German Patent Application No. DE 10 2008 034 847.8 of the Applicant. Therein, drain tabs, also referred to as current drain tabs, of poles of the individual cells are thermally coupled with the cooling plate. Furthermore, the drain tabs are angled such that they are arranged parallel to the cooling plate in positive manner and/or in non-positive manner, the individual cells being electrically interconnected by welding the drain tabs of adjacent individual cells.
Exemplary embodiments of the present invention provide a battery with improved cooling and increased protection against electrical faults, in particular short circuits, which can be produced in a simple manner.
In accordance with exemplary embodiments of the present invention the battery comprises a plurality of individual cells connected in series and/or in parallel to one another, and a cooling plate arranged on the pole side on the individual cells, with current drain tabs of electric poles of the individual cells being thermally coupled with the cooling plate and being angled such that they extend parallel to the cooling plate.
According to exemplary embodiments of the present invention current drain tabs of adjacent individual cells are electrically interconnected in non-positive and/or in positive manner and pressed with the cooling plate in non-positive and/or in positive manner by means of clamping elements. This simultaneous use of the clamping elements for electrically connecting the adjacent individual cells and for pressing the current drain tabs with the cooling plate simplifies the assembly of the battery, which in turn yields a cost savings. Furthermore, in this particular manner, dissipation of heat from the current drain tabs to the cooling plate is improved, since the current drain tabs, owing to lack of material-to-material connections for electrical contacting, such as for example welds, have a flat surface and hence a large heat transfer surface. Additionally, with a use of a heat conducting foil introduced between the current drain tabs and the cooling plate, owing to the flat surface of the current drain tabs, damage to the heat conducting foil and hence electrical short circuits can be avoided.
Expediently, for simple electrical connection and pressing, the current drain tabs of an individual cell are angled by 90 degrees in the opposite direction such that current drain tabs of adjacent individual cells overlap.
To fasten the clamping elements, the current drain tabs and/or the cooling plate preferably have cutouts which correspond to the clamping elements.
According to one aspect of the invention, the clamping elements each comprise screws, rivets and/or spring elements, so that secure clamping of the current drain tabs with the cooling plate and secure electrical coupling of the individual cells can be effected.
Preferably, the clamping elements are, in each case, formed from a pressure bar and screws, the pressure bar having threaded bores that correspond to the screws. In such case, the screws are preferably guided through the cutouts in the cooling plate and the cutouts in the overlapping current drain tabs into the threaded bore of the pressure bar that is arranged beneath the current drain tabs. Due to this embodiment of the clamping elements, a uniform and flat introduction of force likewise ensures uniform and flat pressing of the current drain tabs with the cooling plate, the pressing and the electrical interconnection of the current drain tabs being able to be produced in a particularly simple manner in one operation. Also, due to the clamping elements that can be opened again, simple dismantling of the battery and hence simple exchange and/or disposal of individual cells is possible. Also, before assembling the battery, in particular before fastening and pressing the current drain tabs against the cooling plate, this embodiment of the current drain tabs means that orientation of the individual cells and hence compensation of tolerances is possible.
In order to improve the heat transfer between the current drain tabs and the cooling plate, which is formed in particular from metal, and to electrically insulate the current drain tabs from the cooling plate, an electrically insulating heat conducting body or an electrically insulating heat conducting foil is arranged between the current drain tabs and the cooling plate.
In order to avoid deformations and damage to the heat conducting foil in the region of the screws between the current drain tabs and the cooling plate due to the pressing, additionally advantageously spacer elements are arranged between the current drain tabs and the cooling plate. The spacer elements expediently have cutouts that correspond to the screws, the cutouts in the cooling plate and the cutouts in the current drain tabs. Further, the spacer elements are formed, in particular, of a mechanically resistant material and are of such dimensions that a defined pressing of the heat conducting foil arranged between the current drain tabs and the cooling plate takes place.
In order also to avoid electrical contact and hence electrical short circuits between the clamping elements and the current drain tabs and/or between the clamping elements and the cooling plate, electrical insulating elements are arranged between the clamping elements and the current drain tabs and/or between the clamping elements and the cooling plate according to one aspect of the invention.
In an advantageous configuration of the battery, the current drain tabs, at least in the region of overlap, have an anticorrosion coating, so that corrosion is avoidable and consequently a constant electrical transfer resistance between the current drain tabs can be brought about over the entire life of the battery.
In order furthermore to prevent penetration of foreign matter, in particular dirt particles and moisture, which may likewise result in an increase in the electrical transfer resistance and in electrical short circuits, the current drain tabs, at least in the region of overlap, are sealed off against penetration of foreign matter. For this, electrically insulating sealing elements, paint coatings, silicones and/or potting compounds are provided.
Preferably the individual cells are arranged parallel to one another, so that the current drain tabs of the individual cells are arranged in at least two rows. In order to minimize the weight of the battery and at the same time to ensure effective cooling of the individual cells, one cooling plate in each case is associated with each row of current drain tabs, which plate extends in particular in each case over the surface formed by the overlapping current drain tabs which are arranged in a row.
The battery, according to one configuration of the invention, is a vehicle battery, in particular a battery for a vehicle with electric drive, hybrid drive or a fuel cell vehicle. Preferably the battery is a lithium ion battery. Due to the low weight, the high degree of safety and the reduced costs, the battery is preferably suitable for application in a vehicle.
Parts which correspond to one another are provided with the same reference numerals in all the figures.